Identifying predictors of implant loss in immediate breast reconstruction: integrating surgical and dosimetric factors in a large-scale study

Abstract

Objective: This study aimed to identify surgical and dosimetric predictors of implant loss and establish safety constraints
for patients undergoing immediate implant-based breast reconstruction with postoperative radiotherapy. Methods: This
retrospective cohort study included 292 patients who underwent immediate implant-based breast reconstruction followed by postoperative radiotherapy between 2010 and 2022. Surgical techniques and radiotherapy protocols were
assessed. Radiotherapy dosimetry focused on dose distribution within a 1 cm annular volume around the implant inside
the Clinical Target Volume. Statistical analysis included chi-square, log-rank, and multivariate tests. Results: All patients
received postoperative radiotherapy at 50 Gy in 25 fractions. The implant loss rate was 13%. Univariate analysis showed
a significant association between implant loss and postoperative complications, surgical reintervention, and clinical N
staging (p=0.016). Logistic regression identified postoperative complications (odds ratio [OR] 2.46; p=0.012) and surgical
reintervention (OR 3.51; p=0.007) as independent predictors of implant loss. Among complications, seroma was significant (OR 2.71; p=0.042). Anatomical placement significantly impacted loss rates, with 26% failure in prepectoral vs. 12%
in subpectoral placement (OR 2.46; p=0.035). Dosimetric analysis showed correlation between implant loss and prosthesis volume receiving ≥108% of the prescribed dose (p=0.048) and the 1 cm periprosthetic annular volume receiving ≥108%
(p=0.004). Receiver operating characteristic (ROC) curve analysis identified a threshold of 4.57 cc for V108% in the annular region (area under the ROC curve=0.6459, sensitivity=0.70, specificity=0.57). Spearman’s correlation showed a strong
positive correlation between V108% in the prosthesis and the annular region (ρ=0.682). Conclusion: Postoperative complications, surgical reintervention, and implant anatomical placement were independent predictors of implant failure.
Dosimetric analysis showed that a V108% in the periprosthetic ring exceeding 4.57 cc increased the risk of implant loss,
suggesting this as a valuable dosimetric constraint. These findings support more effective and safer treatment strategies,
potentially transforming clinical practice.